Finalists for the re-design of the Sixth Street Viaduct, a bridge spanning downtown and Boyle Heights, revealed their plans to the public recently. Depending on the mood at the Bureau of Engineering in the coming weeks, we'll soon see three golden "guardian angels"(a proposal by AECOM), a pair of egret's wings (Parsons Brinkerhoff), or a cartoonish row of arches (HNTB) take shape over the LA river.

The winner will be chosen this month, and the entire project, budgeted at $400 million, is scheduled for completion in 2018.

The original Sixth St. Viaduct, as viewed from Boyle Heights.

Archival photo from presentations from the City of LA Bureau of Engineering Sixth Street Viaduct Replacement Project website.

The firms have been tasked with replacing a structure that is already a landmark: at the the time of construction (it opened in 1932), it was the longest concrete bridge in the world, and it was the keystone of a series of infrastructure projects that remade the city for cars. Over the years, the bridge has appeared in everything from Terminator 3 to Kanye West videos. As such, the replacement project was approved only once it was clear that preservation was not an option, due to irreversible decay likened to "concrete cancer" in the original.

But the new designs are united most of all by a thorough re-thinking of the viaduct's purpose, as it's no longer a monument to the automobile's conquest of LA. All three feature bike paths and pedestrian walkways, as well as river access and significant park and commercial space beneath the span. The animated renderings showcasing the designs offer sights never before seen on the Sixth Street Viaduct: half of the bridge closed to traffic, filled with food stalls and women pushing strollers, and a park below the bridge featuring food trucks and kids skateboarding.

AECOM's guardian angels design, as viewed from the planned park beneath the bridge.

Image by AECOM, via presentations from the City of LA Bureau of Engineering Sixth Street Viaduct Replacement Project website.

Functionally, AECOM's design stands out for its separate pedestrian and bicycle bridge suspended below the main structure (in addition to dedicated paths on the top level, featured on all three designs). HNTB imagines pedestrian stairways embedded in the bridge's arches, which would offer the most dramatic view of the city, and a planted median in the bridge's center.

Both Parsons Brinkerhoff and HNTB have also succeeded in re-imagining the bare LA River embankments as a place where people will actually want to linger and congregate: planted terraces lead down to the water, and the Parsons design features a meandering, spiral-shaped diversion from the river's usual flow.

HNTB's DNA-like arches, as viewed from the south.

Image by HNTB, via presentations from the City of LA Bureau of Engineering Sixth Street Viaduct Replacement Project website.

All three designs reference the iconic, asymmetrical steel arches of the original bridge. Here, AECOM's ventures furthest afield, with three gold, tulip-like spires meant to resemble angels. Still, theirs is also the only plan to incorporate actual elements of the original, using a segment of the viaduct's steel arches to complete the bridge's entryway.

HNTB's design is appealing for its lack of pretense -- it is a bridge, not an angel or a bird -- yet it is also out of scale with the half dozen historic bridges that surround it. HNTB has reproduced the Viaduct's arches and multiplied them along the bridge's entire span, looking almost like a giant strand of DNA laid on its side. Parsons Brinkerhoff's mammoth pair of egret's wings offers perhaps the closest re-thinking of the existing Viaduct's design, lifting the arches out of the riverbed and re-creating the same shape above the roadway.

Regardless, come 2018, there will finally be a way to stroll across the LA river without fear of traffic, and to contemplate what the city would be like if we'd been building multi-use bridges all along.